1. Field of the Invention
The present invention relates generally to semiconductor memory and, more particularly, to mixed-mode semiconductor memory that is capable of storing both digital information and analog information.
2. Description of the Related Art
EP Pat. No. 1,124,230 of Winbond Electronics Co., entitled “A Multilevel Message Multilevel Analog Signal Recording and Playback System having Memory Array Configurable for Analog and Digital Storage and Serial Communication”, that is, a prior art technology related to mixed-mode semiconductor memory, discloses a memory system that is composed of a plurality of pieces of non-volatile memory and that can implement the storage of both analog information and digital information in single memory.
FIG. 1 is a block diagram showing the construction of the memory system of the above-described patent. Each memory 212 of a non-volatile memory array 210 is configured to store one type of information, that is, analog information or digital information.
Meanwhile, prior art digital semiconductor memory can store digital information, prior art analog semiconductor memory can store analog information, and the prior art analog/digital semiconductor memory can store only analog information or digital information in a single address space.
Accordingly, in order to process analog information, which has been stored in the prior art analog memory, in a digital domain, or process digital information, which has been stored in the prior art digital memory, in an analog domain, conversion between analog information and digital information using a separate chip is required.
The conversion is problematic in that it requires an amount of time and power that are directly or exponentially proportional to the bandwidth of analog information.